The present invention is directed to silylnorbornane anhydrides and method for making. More particularly, the present invention relates to the hydrosilation of norbornene carboxylic acid anhydride with a silicon hydride in the form of a silane, disiloxane, or polysiloxane.
Prior to the present invention, indirect methods were available for synthesizing silicon functional anhydrides involving the addition of silanes to ortho alkyl substituted aromatic hydrocarbon followed by oxidation of the alkyl groups as shown by J. R. Pratt et al, J. Org. Chem., 38 4271 (1973). Another procedure involved the reaction of maleic anhydride with cyclopentadiene attached by carbon-silicon linkages onto a polysiloxane backbone to produce a siloxane functionalized by 5-norbornene-2,3-carboxylic anhydride groups as shown by L. Ya. Moshinskii et al, U.S.S.R. No. 244616 (1969) [Chem. Abstracts 72, 32777m (1970)].
Direct reaction of unsaturated anhydrides, for example, allyl succinic anhydride with trichlorosilane is reported by Walter Hafner et al, Chem. Abstracts, 212163J, Vol. 91, page 24 (1979). Attempts to directly react silicon hydride with cyclic anhydride having internal aliphatic unsaturation, for example, maleic anhydride and tetrahydrophthalic anhydride to produce silyl anhydrides have been unsuccessful. The reason why direct hydrosilation has been found successful with aliphatically unsaturated cyclic anhydrides having the aliphatic unsaturation in a side chain such as allylsuccinic anhydride rather than internal ring unsaturation, such as maleic anhydride, is not completely understood. One possible explanation is that terminal olefins are much more reactive than internal olefins.
The present invention is based on the discovery that although cyclic anhydrides having internal aliphatic unsaturation normally do not react with silicon hydride, 5-norbornene-2,3-carboxylic anhydride of the formula, ##STR1## where R-R.sup.5 are a members selected from hydrogen, halogen, C.sub.(1-13) monovalent hydrocarbon radicals and substituted C.sub.(1-13) monovalent hydrocarbon radicals, Z is selected from --O-- and C--(R).sub.2, readily reacts with silicon hydride in the presence of a platinum catalyst to produce silyl norbornane anhydrides or dianhydrides.